Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The androgen-signaling pathway is important for the growth and progression of prostate cancer cells. IGF-I and other polypeptide growth factors have been shown to be capable of induction of androgen receptor (AR) activation in the absence of, or at low levels of, ligand. It has been shown that IGF-I increases the cellular level of beta-catenin, an AR coactivator. In this study, we performed several experiments to test whether beta-catenin is involved in IGF-I-induced AR-mediated transcription. We demonstrate that IGF-I enhances the expression of endogenous prostate-specific antigen, an AR target gene, and elevates the level of cytoplasmic and nuclear beta-catenin in prostate cancer cells. Transfection of either wild-type or a constitutively active mutant of the IGF-I receptor augments AR-mediated transcription. An antisense construct of beta-catenin that decreases the cellular level of beta-catenin can reduce IGF-1 receptor-mediated enhancement of AR activity. Moreover, using a pulse-chase experiment, we showed that IGF-I enhances the stability of beta-catenin in prostate cancer cells. Our findings delineate a novel pathway for IGF-I in modulating androgen signaling through beta-catenin.
Mol Endocrinol 2005 Feb
PMID:Beta-catenin is involved in insulin-like growth factor 1-mediated transactivation of the androgen receptor. 1551 31

A new, relatively obscure tumor marker assay, the NMP22 BladderChek Test (Matritech, Inc.), represents a paradigm shift in the diagnosis and management of urinary bladder cancer (transitional cell carcinoma). Specifically, BladderChek should be employed every time a cystoscopy is performed, with corresponding changes in the diagnostic protocol and the guidelines of the American Urological Association for the diagnosis and management of bladder cancer. Currently, cystoscopy is the reference standard and NMP22 BladderChek Test in combination with cystoscopy improves the performance of cystoscopy. At every stage of disease, BladderChek provides a higher sensitivity for the detection of bladder cancer than cytology, which now represents the adjunctive standard of care. Moreover, BladderChek is four-times more sensitive than cytology and is available at half the cost. Early detection of bladder cancer improves prognosis, quality of life and survival. BladderChek may be analogous to the prostate-specific antigen test and eventually expand beyond the urologic setting into the primary care setting for the testing of high-risk patients characterized by smoking history, occupational exposures or age.
Expert Rev Mol Diagn 2004 Nov
PMID:NMP22 BladderChek Test: point-of-care technology with life- and money-saving potential. 1552 21

The pace of development in novel technologies that promise improvements in the early diagnosis of disease is truly impressive. One such technology at the forefront of this revolution is mass spectrometry. New capabilities in mass spectrometry have provided the means for the development of proteomics, and the race is on to find innovative ways to apply this powerful technology to solving the problems faced in clinical medicine. One area that has garnered much attention over the past few years is the use of mass spectral patterns for cancer diagnostics. The use of these so-called 'proteomic patterns' for disease diagnosis relies fundamentally on the pattern of signals observed within a mass spectrum rather than the more conventional identification and quantitation of a biomarker such as in the case of cancer antigen-125- or prostate-specific antigen. The inherent throughput of proteomic pattern technology enables the analysis of hundreds of clinical samples per day. Currently, there are two primary means by which proteomic patterns can be acquired, surface-enhanced laser desorption/ionization (SELDI) and an electrospray ionization (ESI) method that has been popularized under the name, OvaCheck. In this review, an historical perspective on the development of proteomic patterns for the diagnosis of early-stage cancers is described. In addition, a critical assessment of the overall technology is presented with an emphasis on the steps required to enable proteomic pattern analysis to become a viable clinical tool for diagnosing early-stage cancers.
Mol Diagn 2004
PMID:Proteomic patterns as a diagnostic tool for early-stage cancer: a review of its progress to a clinically relevant tool. 1552 21

The nongenotropic ligand estren (Science 298:843-846, 2002) was evaluated for its transcriptional activity mediated by the human androgen receptor (AR). Our results show that estren can bind, translocate, transactivate, and regulate two known target genes of AR in androgen-responsive cell lines. Estren binds recombinant AR with 10-fold higher affinity than either estrogen receptor (ER)-alpha or ERbeta. Estren-bound AR can translocate AR to the nucleus and stimulate the androgen response element-luciferase reporter activity with an efficacy similar to that of androgen. Estren also increased the expression of prostate-specific antigen (PSA) in a dose-dependent manner in human LnCaP cells. Using chromatin immunoprecipitation analysis, we show that the estren-bound AR coimmunoprecipitates with a region of the PSA gene promoter. Therefore, cotreatment with an AR antagonist, bicalutamide, blocked the estren-induced increase in PSA expression. In contrast, phosphoinositol 3-kinase inhibitor wortmannin, or extracellular signal-regulated kinase inhibitor 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophynyltio)butadiene (U0126), and ER antagonist ICI-182780 failed to block the effects of estren. In vivo analysis of estren's action on male-orchidectomized ICR mice revealed estren's AR agonist actions on the levator ani and seminal vesicle target tissues. Taken together, our results reveal the hitherto unidentified genotropic action of estren mediated by AR in androgen-responsive cells and tissues.
Mol Pharmacol 2005 Mar
PMID:The nongenotropic synthetic ligand 4-estren-3alpha17beta-diol is a high-affinity genotropic androgen receptor agonist. 1555 61

The transcriptional activity of the androgen receptor (AR) modulated by positive or negative regulators plays a critical role in controlling the growth and survival of prostate cancer cells. Although numerous positive regulators have been identified, negative regulators of AR are less well understood. We report here that Daxx functions as a negative AR coregulator through direct protein-protein interactions. Overexpression of Daxx suppressed AR-mediated promoter activity in COS-1 and LNCaP cells and AR-mediated prostate-specific antigen expression in LNCaP cells. Conversely, downregulation of endogenous Daxx expression by RNA interference enhances androgen-induced prostate-specific antigen expression in LNCaP cells. In vitro and in vivo interaction studies revealed that Daxx binds to both the amino-terminal and the DNA-binding domain of the AR. Daxx proteins interfere with the AR DNA-binding activity both in vitro and in vivo. Moreover, sumoylation of AR at its amino-terminal domain is involved in Daxx interaction and trans-repression. Together, these findings not only provide a novel role of Daxx in controlling AR transactivation activity but also uncover the mechanism underlying sumoylation-dependent transcriptional repression of the AR.
Mol Cell Biol 2004 Dec
PMID:Negative modulation of androgen receptor transcriptional activity by Daxx. 1557 61

Human androgen receptor (AR) associates with coactivator or corepressor proteins that modulate its activation in the presence of ligand. Early studies on AR coactivators in carcinoma of the prostate were hampered because of lack of respective antibodies. Investigations at mRNA level revealed that most benign and malignant prostate cells express common coactivators. AR coactivators SRC-1 and TIF-2 are up-regulated in tissue specimens obtained from patients who failed prostate cancer endocrine therapy. Increased expression of these coactivators is associated with enhanced activation of the AR by the adrenal androgen dehydroepiandrosterone. Similar association between AR coactivator expression and high prostate cancer grade and stage was reported for RAC-3 (SRC-3). The transcriptional integrator CBP was detected in clinical specimens representing organ-confined prostate cancer, lymph node metastases and tumour cell lines. Agonistic effect of the nonsteroidal antiandrogen hydroxyflutamide was strongly potentiated in prostate cells transfected with CBP cDNA. A functional homologue of CBP, p300, is implicated in ligand-independent AR activation by interleukin-6. The AR coactivator Tip60, which is up-regulated by androgen ablation, is recruited to the promoter of the prostate-specific antigen gene in the absence of androgen in androgen-independent prostate cancer sublines. It was proposed that the cofactor ARA70 is a specific enhancer of AR action. However, research from other laboratories has demonstrated interaction between ARA70 and other steroid receptors. Although in some cases dominant-negative coactivator mutants inhibited proliferation of prostate cancer cells in vitro, confirmation from in vivo tumour models is missing. In summary, several abnormalities in AR coactivator expression and function are associated with prostate cancer progression.
J Steroid Biochem Mol Biol 2004 Nov
PMID:Expression and function of androgen receptor coactivators in prostate cancer. 1566 89

The use of cytotoxic agents to eliminate cancer cells is limited because of their nonselective toxicity and unwanted side effects. One of the strategies to overcome these limitations is to use latent prodrugs that become toxic in situ after being enzymatically activated in target cells. In this work we describe a method for producing tumor-specific toxins by using a ubiquitin fusion technique. The method is illustrated by the production of recombinant toxins by in-frame fusion of ubiquitin to saporin, a toxin from the plant Saponaria officinalis. Ubiquitin-fused toxins were rapidly degraded via the ubiquitin-proteasome system, significantly reducing their nonspecific toxicity. The insertion of the protease-cleavage sequence between ubiquitin and saporin led to the removal of ubiquitin by the protease and resulted in protease-dependent stabilization of the toxin. We engineered toxins that can be stabilized by specific proteases such as deubiquitinating enzymes and prostate-specific antigen (PSA). Both constructs were activated in vitro and in cultured cells by the appropriate enzyme. Processing by the protease resulted in a greater than 10-fold increase in the toxicity of these constructs. Importantly, the PSA-cleavable toxin was able to kill specifically the PSA-producing prostate cancer cells. The ubiquitin fusion technique is thus a versatile and reliable method for obtaining selective cytotoxic agents and can easily be adapted for different kinds of toxins and activating proteases.
Mol Ther 2005 Feb
PMID:Construction of tumor-specific toxins using ubiquitin fusion technique. 1566 31

In this study, we present a novel approach for the induction of tumor vessel thrombosis using genetically modified coagulation factor X. Human factor X was engineered in its activation peptide in a way that it can be specifically activated by prostate-specific antigen (PSA), a tumor-specific proteinase secreted into the bloodstream by prostate cancer cells. For this purpose we inserted different sequences of known PSA cleavage sites from the natural substrate of PSA, semenogelin I, into the activation peptide of factor X. One FX variant (FX-V4) was further optimized by site-directed mutagenesis of the P2 position and the P5 position (FX-V4-P2YP5R). After preincubation with PSA, FX-V4-P2YP5R was able to efficiently induce coagulation in vitro. These FX variants should be useful for site-specific induction of blood coagulation in the tumor vasculature.
Mol Biotechnol 2005 Jan
PMID:Engineering of human coagulation factor x variants activated by prostate-specific antigen. 1566 16

Androgen-independent prostate cancer is a lethal form of the disease that is marked by metastasis and rapid proliferation in its final stages. As no effective therapy for this aggressive tumor currently exists, it is imperative to elucidate and target the mechanisms involved in the progression to androgen independence. Accumulating evidence indicates that aberrant activation of androgen receptor (AR) via signal transduction pathways, AR gene mutation and/or amplification, and/or coregulator alterations may contribute to the progression of prostate cancer. In the present study, the effects of protein kinase A (PKA) signaling and its downstream factors on AR activity at the prostate-specific antigen (PSA) gene were tested. Activation of PKA by forskolin resulted in enhanced androgen-induced expression of the PSA gene, an effect that was blocked by the AR antagonist, bicalutamide. Interestingly, when either p300 or CBP was overexpressed, PKA activation was sufficient to stimulate PSA promoter-driven transcription in the absence of androgen, which was not inhibited by bicalutamide. PKA activation did not significantly alter AR protein levels but significantly increased the phosphorylated form of its downstream effector, cAMP responsive element-binding protein (CREB) in the presence of androgen. Furthermore, chromatin immunoprecipitation showed that the combination of androgen and forskolin increased phosphorylated CREB occupancy, which was accompanied by histone acetylation, at the putative cAMP responsive element located in the 5' upstream regulatory region of the PSA gene. Remarkably, mammalian two-hybrid assay indicated that p300/CBP may bridge the interaction between AR and CREB, suggesting a novel enhanceosomal cooperation. These results demonstrate an intriguing interplay between a signal transduction pathway, coactivator overexpression and AR signaling as a possible combined mechanism of progression to androgen-independent prostate cancer.
J Mol Endocrinol 2005 Feb
PMID:The role of protein kinase A pathway and cAMP responsive element-binding protein in androgen receptor-mediated transcription at the prostate-specific antigen locus. 1569 81

G3139 is a BCL-2 antisense oligonucleotide whose antitumor effects in preclinical models are enhanced when combined with taxane-based chemotherapy. This trial determined the safety and biologic activity of G3139 given with paclitaxel and docetaxel for the treatment of progressive solid tumors. Three cohorts of patients received weekly paclitaxel 100 mg/m2 on days 1, 8, and 15 concurrently with a 21-day continuous infusion of G3139 at 4.1, 5.3, and 6.9 mg/kg/d, depending on the cohort. Two subsequent cohorts received docetaxel (75 mg/m2) on day 5 of a 5-day infusion of G3139 at 5 or 7 mg/kg/d. Bcl-2 protein levels in peripheral blood mononuclear cells (PBMCs) were assayed on an exploratory basis. Fifteen patients were treated. Eight received a total of 14 cycles of G3139 and paclitaxel; seven received a total of 22 cycles of G3139 and docetaxel. Eight patients required dose modifications for either grade 4 neutropenia (6 patients) or grade 1-2 reversible transaminitis (2 patients). No radiographic responses were seen, although two of the six taxane-naive prostate cancer patients exhibited a prostate-specific antigen decline greater than 50%. Bcl-2 protein levels in PBMCs declined with treatment as assessed by immunohistochemistry. The authors conclude that G3139, whether given as a 5- or 21-day infusion, is well tolerated with taxane chemotherapy and is biologically active by immunohistochemistry at doses up to and including 7 mg/kg/d, using weekly paclitaxel (100 mg/m2) or docetaxel every 3 weeks (75 mg/m2). These data support the dose selection of ongoing phase 2 studies of G3139 at 7 mg/kg/d and docetaxel 75 mg/m2.
Appl Immunohistochem Mol Morphol 2005 Mar
PMID:Safety and biologic activity of intravenous BCL-2 antisense oligonucleotide (G3139) and taxane chemotherapy in patients with advanced cancer. 1572 87


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